<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="utf-8">
	<title>Document</title>
	<style type="text/css">
		.clearfix:before{
			content: "";
			display: 
		}


		.con{
			width: 300px;
			height: 300px;
			background-color: gold;
			/* 解决塌陷的第一个方法 */
			/* border:1px solid #000; */
			/* 第二种解决塌陷的方法 */
			overflow: hidden;
		}

		.box{
			width: 200px;
			height: 100px; 
			background-color: green;
			margin-top:100px;
			margin-left: 50px;
		}

	</style>


</head>
<body>
	<div class="con">
		<div class="box"></div>
	</div>


</body>
</html>